I've been trying to work something up running httpd -X, unfortunately,
single user access doesn't seem to help. As near as I can tell, it
happens only with concurrent access. Perhaps some type of memory lock
or something. I no longer have "--with-mm", so it's not trying to use
that type of shared memory.

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Can gdb help with running httpd *without* the -X?
I've tried ab, but I think I'm going to try again (running ab multiple
times on different pages to try and simulate real world access) and see
if I can get anything to come up there. Again, concurrent access seems
to be the key as I have been unable to get Apache(PHP) to segfault on a
test server with single access only.
I took a look at the PostgreSQL session code on Zend (which I believe
you've written)... The one's I'm using are quite a bit similar, though
yours track counts and such. The core reading/writing is similar,
except for the following: The Zend version will still load a session up
even if the maxlifetime has been exceeded. Since gc isn't called EVERY
time (unless probability is 100), occasionally there could be the
possibility of stale session data being loaded up. This is a simple one
to fix, but important for me. I notice that you have the row locking in
the SELECT for the session_read. Will this cause PostgreSQL to deny
read access for another concurrent connection (with the same
session_id), or will that second connection wait until the first is
done? I guess I'll have to test that out. If you want, I can switch
over to your code and to prove it's not the session_handler code itself.
How busy are the sites you maintain that use the session handler code?
(In requests per minute, etc.)
I noticed your comment on the mm code. Like I said, I was a bit
confused on that as well. I can certainly write a bug report up for
that, but I don't know if you'd classify that as a bug.
Jaime Bozza
-----Original Message-----
From: Yasuo Ohgaki [mailto:[EMAIL PROTECTED]]
Sent: Thursday, December 13, 2001 1:01 PM
To: Jaime Bozza
Cc: [EMAIL PROTECTED]
Subject: Re: [PHP] Re: PHP 4.1.0 and User-defined Sessions
Jaime Bozza wrote:
> I *HAVE* searched the database and there have been similar problems,
> with the request to try the latest CVS and to produce a short script
> that duplicates the problem. Since I can't exactly put the CVS
version
> onto a live website (and start having all sorts of other problems) and
I
> can't duplicate the problem consistently on a "non-active testing"
site,
> I don't really have anything else additional to offer except for "Me
> Too!".
>
> My email already stated that I have tried to use --enable-debug and
that
> I'm getting a segfault without any core file whatsoever. The last
> paragraph explains my attempts on using enable-debug.
This is not practical, but you can try to run apache under gdb.
If any segfault happens while you are running apache under gdb, you can
get backtrace.
BTW, did you try benchmarking tools like ab?
You may be able to reproduce problem with benchmark tools.
--
Yasuo Ohgaki
>
> Jaime Bozza
>
>
> -----Original Message-----
> From: Yasuo Ohgaki [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, December 12, 2001 9:04 PM
> To: [EMAIL PROTECTED]; Jaime Bozza
> Subject: [PHP] Re: PHP 4.1.0 and User-defined Sessions
>
>
> Search bug database to see if the same problem is reported or not.
>
> If you get segfault, buld PHP with --enable-debug and get core file.
If
> it is new, get backtrace as described in bugs.php.net. Submit new bug
> report. If you found multiple issues, submit bug report separately.
>
> There are more comments following.
>
> Jaime Bozza wrote:
>
>
>>Hello,
>> I've run into a really intermittent and strange problem with PHP
>>4.1.0, and before I try and figure out how to send in a bug report
>>that'll get ignored (because I don't have all the data that is
>>expected), I thought I would try here to see if anyone else is having
>>similar problems.
>>
>>
>> Configuration: FreeBSD 4.4-STABLE, PostgreSQL 7.1.3, Apache 1.3.22,
>>
>
>>PHP 4.1.0.
>>
>>
>
>
> So far I don't have problem with Linux 2.4.4/PosrgreSql 7.1.3/Apache
> 1.3.22/PHP 4.1.0 or 4.2.0-dev
>
>
>
>> I use PHP Sessions for large parts of our sites. I'm currently
>>using the PostgreSQL Session Handler code from Jon Parise and it had
>>been working pretty much perfectly under PHP 4.0.6. (The only issue
>>was when multiple requests came in with the same session_id at the
>>EXACT same time - AvantGo for instance - But I made some minor
>>modifications to eliminate that problem)
>>
>> Once upgrading to 4.1.0, I started noticing Apache processes
>>segfaulting left and right. (Signal 11's, with the occasional Signal
>>10) At first I started to think perhaps memory was bad on that
>>particular system. I have 4 servers (running 3-5 separate Apache
>>processes each) and each and every server was giving me the Signal
>>10/11's. I started looking into it further.
>>
>> I have an auto_prepend for my "application" code that defines the
>>base session variables, config variables, includes the
>>pgsql_session_handler file, etc. All the processing is handled here
>>so that my other pages can just use an array that stores all the
>>session data. That way I can pretty much ignore the backend in any of
>>
>
>>my application code.
>>
>
>
> This setting is similar to mine also.
>
>
>> Once I turned this code off, bingo! No more segfaults! So I
>>started hacking out code there. If I kept all the startup code but
>>eliminated the session commands, it still worked. As soon as I turned
>>
>
>>on the session (session_start/session_register), I'd get the segfaults
>>
>
>>again.
>>
>
>
> If you could make *short* script that segfault, attach it to bug
report.
>
>
>> If I turned off the pgsql_session_handler and went back to files
>>(the default), I didn't have any problems either. It was just a
>>problem when I was using the pgsql_session_handler.
>>
>
>
> I'm not sure what your session handler looks like, could try pgsql
> session handler that can be found at Zend.com's code exchange?
>
>
>
>> So I then turned off session handling and built my own session
>>functions (quickie, but basically emulate the session functions I
>>needed) that called the SAME pgsql_session_handler code that was being
>>
>
>>used by PHP's internal functions. For the past hour I haven't had a
>>single segfault on any of my servers. (Within 5 minutes of turning on
>>
>
>>the internal session routines, I would start getting segfaults every
>>minute or so)
>>
>> One other thing I noticed was that I had compiled PHP with the mm
>>shared memory library. Previous to 4.1.0, each Apache process had a
>>size of around 64MB. (Without mm, the size was 4-5MB or so) Once
>>installing 4.1.0, the size went up to >130MB for each process! Since
>>I believe sessions utilize the mm library if it's available, I figure
>>this may be one of the clues. (I never tried using the shared memory
>>style of sessions, so I couldn't tell you if it would segfault there.)
>>
>
>
> This is strange, mm session module allocates shared memory that is
> needed. (Description is not fully correct, but almost correct)
>
>
>> Is anyone having any of these problems? Is anyone else using the
>>internal PHP session support with their own session handler (under
>>some of the same conditions I gave above) and having no problems with
>>PHP4.1.0? Please let me know either way.
>>
>> BTW, I never get a core file. I've tried "enable-debug" to get the
>>symbols in there, but without a core file I'm kind of out of luck on
>>tracing. All I can tell you now is that using user-defined handlers
>>for sessions started causing me lots of problems. (As near as I can
>>tell, you need to have some sort of a decent load on your servers -
>>Single client access didn't ever seem to allow me to force the
>>crashes)
>>
>>
>
>
> You can run httpd under gdb and can take backtrace. Try.
>
>
--
Yasuo Ohgaki
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